800 PERIDINEAE OF NEW SOUTH WALES, 



conica, angulata, tabulis concavis, ad apicem fovea instructa 

 apice interdum producto; tabulis aequatoriis 7, apicalibus dorsali- 

 bus 3, ventralibus 2. Hypovalva valde angulata, tabulis con- 

 cavis; pone in spinas 2-3 protracta. 



Long. 30, lat. 21-25, epiv. alt. 15-17 ^. Sydney Water Supply 

 (64, 66) . 



Syn. P. tabulatum v. caudatum Playf., I.e., p. 544, PI. lv., f. 

 18. A small form and rather rare even in the slimes from the 

 Sydney Water filters. The cell is ovate, strongly faceted, with 

 concave plates. The epivalve almost triangularly conical with 

 an apical pit. The apex is sometimes produced. Hypovalve 

 depressed, very angular, with angles produced backwards into 

 2 or 3 short spines, plates concave. Membrane smooth. 



Peridinium caudatum var. guildfordense, n. var. (Text-fig. 5).* 



Peridinium minutum, subglobosum (vel ovale), glabrum, ubique 

 rotundatum; fossa transversa tenui, modo spirali fere circulata. 

 Epivalva conico-rotundata, lateribus, asymmetrice arcuatis, fovea 

 subapicali instructa; tabulis asquatoriis pentagonis 7; apicalibus 

 4 magnis hexagonis, ventralibus 2, dorsalibus 2; tabula singula 

 dorsali pentagona (fere quadrata) pro tabulis ventralibus dis- 

 posita. Hypovalva tenuis, paene scutelliformis, quam epivalva 

 angustior; tabulis asquatoriis 5, antapicalibus 2, non omnius 

 asqualibus, modo oblique dispositis; fossa longitudinali brevi. 



Long. 19-31^, lat. max. 17-28i ^. 



Guildford (70); Auburn (148); Fairfield (83); Botany (17); 

 Rookwood; Centennial Park (133) ; Lismore (308, 316, 327, 337, 

 347). 



A minute form first obtained in considerable quantity from 

 a pool at Guildford. The general shape is so very broadly 

 ovate as to be almost globose, and smoothly rounded everywhere 

 but slightly faceted in the hypovalve. More oval specimens are 

 also met with however. Transverse furrow very shallow, the 

 longitudinal furrow short and distinctly defined. Hypovalve 

 very much smaller and decidedly narrower than the epivalve, 

 convex behind. The sides of the epivalve are unequally arched, 

 the left side (in dorsal view) being flatter than the other, and 

 on this side is found a slight pit which is therefore subapical. 

 The outlines of the plates are often very delicate and with diffi- 



*In all the text-figures read thus : (a) dorsal view, (d) ventral view, 

 c) epivalve, (d) hypovalve, unless specified otherwise. 



